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Personality > Biological Bases of Personality > Flashcards

Biological Bases of Personality Flashcards

1
Q

Whats the problem with looking for family resemblance as an indicator of genetics?

A

Could be resemblance for reasons other than genetic

  • i.e. children’s personality can elicit certain behaviours from parents that lead them to resemble each other
  • or parents provide an environment that encourages children to become like them
    ex. Bach’s family
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2
Q

3 factors involved in Personality

A
  1. Genetics
  2. Shared Environment
    - Things in the environment that makes us like others who share that same environment
    - I.e. parents, schools, cultures, country
  3. Non-shared Environment
    - Things that happen to us uniquely and shape us in directions that are different from others
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3
Q

define Phenotype

A

Set of all Measureable or observable aspects of who we are

- hair color, eye color, IG, Personality(may not be observable but definitely measureable)

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4
Q

Define genotype

A

Set of genes we have inherited from our parents

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5
Q

if some phenotypic characteristic (say, intelligence or IQ) is completely determined by genes, then the correlation between IQ scores of MZ twins reared apart, and the correlation between IQ scores of MZ twins reared together should be What?
- what do we actually see?

A

should both be equal to 1.00

→ We do not see this, there is lower correlation for those raised apart thus there is an affect of environment

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6
Q

if we compare the phenotypic similarity of MZ twins with that of DZ twins (with both sets either raised apart or raised together) assuming 100% genetic determination, then we still expect to find a _____ correlation between the scores of MZ twins, but only a ___ correlation between the scores of DZ twins

A

1.00, .50

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7
Q

if a phenotypic characteristic is 100% determined by genes, we expect there to be essentially __ correlation between children and their adoptive parents, but a ____ correlation between children and their biological parents.

A

0, 50%

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8
Q

What are the problems with twin studies?

A

→ DZ twins (of the same sex) confused as MZ
= underestimate influence of genes
ALL other problems lead to overestimate of genetic influence
→ Selective placement: Correlated environments in adopted twins
→ Differences between MZ and DZ twins in environmental similarity
→ Assortive Mating: Greater parent-child similarity

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9
Q

the total variance (VT) of a distribution is equal to …

A

to the sum of the genetic variance (Vg) and the environmental variance (Ve)

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10
Q

Define hereditability

A

portion of total variance that is due to genetic variability in the population at large

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11
Q

what is The heritability coefficient for some phenotypic characteristic

A

the ratio of the genetic variance (Vg)to the total variance (VT).
→ h2 = Vg/Vt

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12
Q

what equation is used when the data available consists of correlations between pairs of monozygotic twins reared apart (MZA).

A

→ h2 = r(mza)

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13
Q

What equation is used for calculating the heritability coefficient when the data consists of DZ twins reared apart (DZA).

A

→ h2 = 2r(dza)

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14
Q

What equation is used when the data consists of both correlations between pairs of monozygotic (MZ) twins, and pairs of dizygotic (DZ) twins. It doesn’t matter whether the twins have been reared together or apart, so long as both groups of twins have been reared in the same way (together or apart).

A

→ h2 = 2(rmz – rdz)

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15
Q

→ The heritability quotient merely tells what?

A

how much of the total variability in some phenotypic characteristic can be attributed to genetic variability within our sample.

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16
Q

Does heritability apply to groups or individuals

A

GROUPS

- If a group shows that 50% of IQ is due to genes, it does not mean 50% of your genes are from your parents

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17
Q

• Heritability Coefficient is NOT a constant, how does is vary?

A

Varies from population to population, and over time

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18
Q

→ Whenever you get MZ correlation more than ____ the correlation of DZ twins means there is a problem with your data

A

half

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19
Q

There are 2 limits to our interpretation of the heritability coefficient, explain.

A
  1. h2 tells us nothing about how much of an individual’s phenotype can be attributed to his or her genes: h2 is about the source of variation between individuals.
  2. h2 is not a constant. The relative contribution of genetic variability to phenotypic variability may change over time, and may be different in different populations.
20
Q

what is Temperament

A

Something general about an individual’s behaviour/personality

21
Q

what did Thomas, Chess and Birth (1970) do?

A 
Tested 9 personality traits on a 3 point scale(high,medium, low) for 9-10month old infants for their: 
• Level of motor activity
• Positive response to new objects
• Regularity in biological functions
• Friendliness or good mood
22
Q

what did Thomas, Chess and Birth (1970) find?

A 
2 major clusters of variables that were highly intercorrelated traits:
EASY infants
•	Regular rhythms
•	Good mood
•	Accepts novelty
•	Adapts well to change
•	Low to moderate levels of energy
→ laid back, easy to deal with infants
DIFFICULT infants
•	Irregular rhythms
•	Poor mood – often cry
•	Dislikes novelty
•	Adapts poorly to change
•	High levels of energy
23
Q

what happened when they They assessed these individuals all the way to 14 -15

A

→ It is consistent: They found a high correlation b/w their ratings at age one and groupings at age 14
→ It causes differences is psychology: ?? difficult infants showed various kinds of psychological problems and only 20% of easy infants were referred for help
→ also premature infants are more likely to be classified as difficult and the bulk of them retain the same grouping at 4.5 years, while some did change
→ they were interested in those who change from difficult to easy – and the only difference is that they had especially warm and present mothers

24
Q

what is a contrast effect

A

DZ correlations are much smaller than they should be (much less than half the MZ correlation) given the relative genetic similarity of MZ and DZ twins.

25
Q

Buss & Plomin (1984)

Say there are 3 general aspects of temperament

A
  1. Emotionality (similar to neuroticism)
  2. Activity
  3. Sociability
26
Q

what is the EAS survey

A

20 statements that is taken by the child/infant’s parent (7 for each scale) (emotionality, activity, sociability)

27
Q

Whats the 1st reason Why do we see contrast effects?

dominant/recessive/ epistatic

A

Non-Additive genes: Effects on our phenotype that depend on interactions between genes.
1. Dominant – Recessive Effects: depends on what allele is present from our parents
2. Epistatic Effects (are those in which the expression of one gene is affected, not by its other copy or allele, but by a gene in some other location):
• The genes affecting each other have different Loci

28
Q

Why are non-additive effects a problem in calculating heritability?

A

MZ twins share 100% of both additive and non-additive genetic effects, DZ twins (and other siblings) share 50% of additive effects, but only 25% of non-additive effects(dominant –recessive, or epistatic effects)
This is a problem because traditional formulas for heritability assume 50% genetic similarity between DZ twins.

29
Q

what are Epigenetic Effects?

A

→Chemical instructions of gene expression (whether to turn genes on or off)
→ Differentiates cell types in organs
→ Heavily influenced by environments
→Passed on to offspring: Your parents epigenomes effect your epigenome as well (so their experiences influence your epigenome)

30
Q

do MZ twins share epigenetic effects?

A

→ MZ twins don’t share 100% of epigenetic markers (at least in term of which genes are turned on)
→ Means identical twins are not identical! We don’t know how similar they are!

31
Q

Whats the 2nd reason Why do we see contrast effects?

A

is violations of the equal environments assumption:
→ But parents of DZ twins often work hard to differentiate their environments to emphasize their uniqueness - a phenomenon called a contrast effect.
→ parents of MZ twins often work to make their two environments even more similar than they would otherwise be - a process we call assimilation

32
Q

How did Kagan classify the children he observed orginally

A

Some show fear in most situations: Inhibited (10%)
Some show no fear in any situation: Uninhibited (20%)
Remainder show mixed reactions: Middling (70%)

33
Q

what are typical behaviours of Inhibited Children

A
  • Slow to start conversation with unfamiliar adult or peer
  • Seldom smile spontaneously with unfamiliar other
  • Slow to relax in unfamiliar situations
  • Memory impaired following stress
  • Cautious decision makers (low risk takers)
  • Unusual fears or phobias
34
Q

what is the Physiology of inhibited Children

A
  • HR up during stress/ stand up
  • Diastolic BP up when stand up
  • Pupillary dilation under stress
  • Higher muscle tension
  • Higher right frontal cortex activation (negative emotions)
  • More allergies – (ties to immune system)
  • More activity in HPA axis (active during stress), RAS (like introverts), ANS (sympathetic branch)= responsible for arousal/flight or fight system
35
Q

Inhibition and ‘Somatotype’

→what are the relationships between behavioral inhibition and several other aspects of appearance and body shape

A
  • 60% of inhibited children have blue eyes
  • 60% of uninhibited children have brown eyes
  • More kin (relatives) of inhibited children have blue eyes; of uninhibited have brown
  • Inhibited boys have narrow faces, thin builds (lean)
36
Q

what were the four groups that can be used to predict likelihood of inhibition?

A
  1. Low reactive (40% of sample)
    - low motor and low distress
    - most likely to be uninhibited
  2. distressed (25%)
    - high distress, low motor
    * 55% turned out to be uninhibited - most likely IN THIS STUDY to be uninhibited
  3. Aroused (10%)
    - high motor, low distress
  4. High reactive (25%)
    - most likely to be inhibited
    - high distress, high motor
37
Q

what did Loehlin & Nichols (1976) find in their stud using 17 yr olds who took the NMST

A

• high h2 for male twins,
• large contrast effects in the male twin data
- not so with female twins
→ lower estimate of h2 for females than males. overestimate contribution of genetics for males
• L&N concluded that the average heritability coefficient for personality characteristics was about 50%.

38
Q

is temperament consistent?

A

relatively consistent across the next 10-15 yrs but can change based on life experiences (nurturing, parenting, relationships with peers)
- A lot of this is due to epigenetic mechanisms (and we know life experiences turn genes on and off)
→ Example: stress turns genes on and off

39
Q

when Scarr et al (1981) Compared two groups of families (w 18yr kids) on heritability estamates for personality, what did they find?

A

→ Heritability Estimates for personality:
• .22 (parent-child similarity)
• .26 (sibling-sibling similarity)
→ about half the heritability from twin studies
*shows that h2 estimates for twin studies are too high

40
Q

what were the correlation results for the Swedish Adoption/Twin Study on Aging (SATSA)

A
  • MZA: .25 (b/c older = more life experiences)
  • DZA: under .4
  • MZA vs. DZA apart: .5 (saying much more variation occurred due to experience)
  • MZT vs. DZT: .7 and .8 (less accurate b/c MZ have more similar environments)
41
Q

what are the Shortcomings of H2 Calculations

A

• Ignores environmental effects that bias calculations:
- Assimilation (MZ twins)
- Contrast (DZ twins)
• Assumes only additive genetic variance
- non-additive effects are assumed to be zero
- epistatic effects effects assumed to be 0
• No separate calculation for shared vs. non-shared environmental effects (wheras SATSA data did)

42
Q

what were the SATSA variences found?

A

→ 29% genetics
→ 9% shared environments
→ 62% Non-shared Environment and error

43
Q

what are some Non-shared Environmental Effects

A
  • Differential treatment by parents
  • Different interactions with siblings
  • Birth order (extensive literature on 1st borns, middle borns etc.)
  • Sibling age spacing – you have very different role depending on spacing
  • Gender differences (may be complex interaction with spacing)
  • Different school experiences
  • Different friends, playmates
44
Q

Give example of how dominant-recessive genes can lead to contrast effects

A
  • each twin has a recessive allele for blue eyes (Bl).
  • One twin has an additional Bl showing in her phenotype as blue eyes
  • The other has a dominant Br allele giving her brown eyes
    = Though they have 50% genes in common (each have a Bl) their phenotype is 0% similar
45
Q

what were the Satsa Variances for genetics, shared environments and non shared environments?

A

→ 29% genetics
→ 9% shared environments
→ 62% Non-shared Environment and error

46
Q

Which of the theorists did NOT explicitly recognize the role of biological or genetic factors in personality?

A

bandura and mischel

47
Q

What type of personality are inhibited children according to Eysneck’s model

A

Neurotic introverts

Personality (9 decks)

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